Hydrocarbon oil treatment



Patented June 30, 1936 UNITED STATES PATENT OFFICE HYDROCARBON OIL TREATMENT No Drawing. Application March 28, 1933, Serial No. 663,244

20 Claims.

The present invention relates to the art of mineral oil refining, and has particular reference to the separation of crude petroleum or petroleum products into fractions of different chemical composition while of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products, particularly oils of substantial viscosity, are separated into various fractions by means of fractional extraction with a diketone, and more particularly acetyl acetone, or a mixture of solvents containing substantial amounts of diketones. The term diketone as used herein comprehends one or a mixture of two or more diketones. Specific examples of other diketones that may be employed in my process are diacetyl and acetyl methyl ethyl ketone.

It is recognized in the art that mineral oils, such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example, as paraffins of the general formula CnH2n+2, olefines of the general formula CnH2n, hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large number of individual compounds of each series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely, parafiinic base, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the paraffin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and a low hydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continent oil fields, contain hydrocarbons in proportions intermediate these two extremes.

The variance in the proportion of the different series of hydrocarbons in paraffinic, naphthenic, and mixed base oils is evidenced by the physical properties of the various oils and particularly by the relationship of the specific gravity to the viscosity of one oil as compared with another. For example, oils derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt universal at 100 R, will show a specific gravity at F., of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf Coast area, will show a specific gravity of about 0.933 at 60 F. 5 The relationship between the viscosity and gravity indicates the degree of paraflinicity or naphthenicity of the oil, and such relationship may be expressed by the viscosity-gravity constant as hereinafter described. 10

If a given crude petroleum be distilled into successive fractions and the specific gravities and viscosities of the several viscous fractions be determined, it will be found that they conform to the general relationship expressed by the for- 15 mulse G=a+ fglog (V-38), or G=0.24+

0.755a+0.022 log (V35.5) 2

in which G is the specific gravity at 60 F., V" and V' are respectively Saybolt universal viscosities at F. and 210 F., and a is a constant known as the viscosity-gravity constant. Viscous fractions from each of the different types 25 of crude have different viscosity-gravity constants. While, in general, viscous fractions from a single crude have substantially the same viscosity-gravity constant, such constant is lower for fractions of paraflinic crudes than is the constant for fractions of the naphthenic crudes. An article entitled The viscosity-gravity constant of pertroleum lubricating oils by J. B. Hill and H. B. Coats, which will be found in volume 20, page 641 et seq., Industrial and Engineering Chemistry for June, 1928, explains the determination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an index of the paraffinicity or naphthenicity of viscous oils, since when a given crude is distilled, the fractions thereof collected, and the specific gravity and the viscosity of each of the viscous fractions determined, such specific gravities and viscosities substituted in the formula, and the viscosity-gravity constants of the fractions calculated, it will be found that such constants are substantially the same.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067 Burbank (Mid-Continent) 0.8367 Guadalupe (Gulf Coast) 0.8635 Mirando (Gulf Coast) 0.9025

7 while the above figures indicate the viscositygravity constants of specific oils from. several types of crudes, it is to be understood that for any'particular type of crude such constant may a much more naphthenic.

be within a range between values above and below the constant of'the typical crude given. For example, viscous oils resulting from the distillation: of Mid-Continent crudes have viscositygravity constants 1 ranging from' about .835 toabouty855, whereas the viscous fractions resulting from the distillation of Pennsylvania type 'crudes range from about .805. to--about -=.828,-and

in most instances, are below .820. Oils are in-f creasingly paraffinic as their viscosity-gravity constants decrease. a

My invention is based upon the discovery'that oils containing both the parafiinic series: of=hydrocarbons and the various naphthenic iseriesz' may be fractionally extracted with a diketone.

The various series of hydrocarbons possess a dif-' ferentialsolubility in such solvent, the maphthenic:;-hydrocarbons being much more soluble therein than the parafiinic hydrocarbons. By means: of: extraction with such solvent, it, is therefore possible toiefiect a'partialseparation of the naphthenic hydrocarbons -from the. paraffinic,

'andqto. obtain fr0m;an oil containing both classes v: of. hydrocarbons; an .oilswhi'ch is; much more pare affinicithan:.thel-originalczoil;and one which is 'By. my invention, for example-mt,islipossible to produce an oil ofthe quality normally.:.:0btained from: Appalachian crude's; from:.crudes..of the mixed base type fromgithe ;Mid.-;Continent. 1 area, and, conversely,

. to'iobtain oils .fr0m .mixe d-. base crudessuch as are normally obtained from the naphthenic .oils; of the Gulf Coast area. In generaL'from oils from any source there.mayfieuobtained"byJnyI.

process, oils which are respectively more paraffinic and more naphthnic than the oil normally obtained from such' 'source bydistillation. V

In accordance with my invention, I first mix the oil to 'be treated with a suitable proportion of the solvent at a temperature suchthatcomplete solution-is effectedand a homogeneousliquid obtained. 'Itheircool themixture to a temperature at which separation-oithehquid: into a -twolayer system-.will take-place; The upperlayer wi'll contain a relatively small amount-of .the

solvent dissolved "in the 'parafiinic portion of the oil while the-lower layer -will contain the-morenaphthenic '-portion-..o J the oil dissolved in the 1 solvent-anal may agitate the mixture of solvent and oil at temperatures atwhich the liquids are only partially miscible,-and-rtherebyefiect solution of the naphthenic portion of the oil in the solvent. In either of the above procedures I may take advantage :of; the principles of c'ountercurrent extraction x ier th b /iamb c r e-9 Q si l r t lation ranges but of different .chemicalcompositions. and .difierentp ySical characteristics.

quantity of solvent and repeat the extraction,

thereby to. .remove additional naphthenic 1 constitu'ents -frornlsaid..laye'r1.: @The extraction istep S mayisb'e repeated any desired Cnumber of times, 1 eacrc repetition. producingoan oil': of higher .paraf,

.After. .the. extraction. proper, .I effect separation I ofhthagtwodayers .which. form, .by; any. suitable, procedure,- .as for,,; example,. by decantatiorr. I. n emove rom each; oi. he pa at d ye s. the pgrtionofsolventwhich :each contains by;

' 1 suitable .procedure, such as byevacuum. distilla-,--

cause such layer to besolid or semi-solid, Such.

layer may be separated into solid and liquid hydrocarbons by any of the well-known dewaxing processes such as by cold-settling or by centrifuging. In many instances it maybe advantageous-todewaxthe oil prior to extraction. However, it is to be understood that in accordance 'with'myinventio'n, ,dewa'xing may be effected either-.priorxor subsequent to extraction.

My invention'will be further understood from the :followingspecific example:

.-100'.parts of a Mid-Continent distillate having, a viscosity of 305 seconds Saybolt universal at 100FI, a specific gravity of 0.909 at 60F and a viscosity-gravityconstant of 0.853; was mixed witho300 parts *of tacetyl acetone and heated to slightly-above the 'temperature'of complete miscibility; whichlwas approximately 38 'C.' The homogeneous liquidwhich resulted was cooled with agitation to 15C., and allowed tosettle",

whereupon a two layersystem formed. After 5 separation, the layers were each freed of solvent by vacuum distillation The undissolved oil fraction comprising 30.0% of the stock had a viscosityiof 229 seconds Saybolt universal at 100" R,

a specific gravity of 0.880, and aviscosity gravity constant 01 0.823. i The dissolved oil'fraction com prising 70.0% of the stock had'a viscosity of 314 I seconds Saybolt universal-fat 100- F., a specific;

gravityiof 0.917 andaviscosity-gravity constant Fromthe 'above' example it will be noted that] by extraction-of anoil with acetyl acetone, there 7 may be obtained oil fractions which are respecti'vely more para'ifinicand=more naphthenic than the original-oil.- Byrepetition of the extraction processupon the undissolved'fraction, oilsof even greater'parafifinicity will result. 7 g

My process is practically independent of the particular nature or sourceof the crude oil or oil fraction to be extracted.- There may be produced by "my process oilproducts of desired characteristics from oils which by distillation will not produce such products.

' Hereinabove,mixtures-ofsolventshav'e been I referred to. It is to be understood that in'such mixturesthe constituents ,will not react with i one another nor 'wi-ththe oil upon-whichthey are to beused, and'that "such mixtures will. contain substantial amounts of diketones.

For brevityyin the appended claims diketone. is employedin ageneric sense to include one or:

a mixture of 'diketones, or 'a" mixture of: solvents containing substantial": amounts of diketones.

Furthermore, diketone; as employed herein comprehends ketones possessing the formula.

and/or R' are similar or dissimilar'hydrocarbon radicals Also wh en in the appended iclaimssoil is spe -f cifically referred to-as being viscous, itis tobe understood that'theoil is of substantial viscosity, i.e.-, of-the order .of:. 50 seconds at 100. F or more. 7

What -I.claim'is: .v V 1.1 In the art of. refining ;mineral"oils,' the process :whichzzcomprises separating an oil.;contain.-:'v ingr paraifinicand naphthenic hydrocarbons into Saybolt universal fractions respectively richer in paraifinic and naphthenic compounds by extracting said oil with a diketone.

2. In the art of refining mineral oils, the process which comprises adding a diketone to an oil containing paraifinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form a twolayer system, and separating the upper layer from the lower layer.

3. In the art of refining mineral oils, the process which comprises adding a diketone to an oil containing paraifinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form a two-layer system, removing the lower layer, and similarly re-treating the upper layer with a diketone.

4. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing paraifinic and naphthenic hydrocarbons into contact with a diketone thereby to effect solution of a portion richer in naphthenic hydrocarbons in the diketone, separating the solution so formed from the remainder of the oil, and removing the diketone from both portions of the oil, thereby to obtain fractions of the oil respectively richer in paraifinic and naphthenic hydrocarbons.

5. The process for separating mineral oils containing paraffinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with a diketone thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the diketone, separating the solution so formed from the remainder of the oil, and distilling the diketone from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

6. The process of treating a viscous fraction of a crude oil of one type containing paraflinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater content of paraffinic hydrocarbons, which comprises extracting the viscous fraction with a diketone, and separating the oil so treated into portions respectively richer in paraifinic and naphthenic hydrocarbons.

7. In the art of refining mineral oils, the process which comprises bringing a diketone into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing parafiinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania typ-e crude by distillation.

8. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contact with a diketone thereby to efiect solution of a portion richer in naphthenic hydrocarbons in the diketone, separating the solution so formed from the remainder of the oil, and re-treating the oil with additional amounts of a diketone.

9. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing paraffinic and naphthenic hydrocarbons into contact with acetyl acetone thereby to effect solution of a portion richer in naphthenic hydrocarbons in the acetyl acetone, separating the solution so formed from the remainder of the oil, and removing the acetyl acetone from both portions of the oil, thereby to obtain fractions of the oil respectively richer in paraffinic and naphthenic hydrocarbons.

10. The method of producing parafiinic lubricating oil from mixed base crude which comprises distilling the crude and bringing a portion thereof into contact With acetyl acetone, thereby partially dissolving the oil, separating the acetyl acetone solution of oil so treated, and removing the acetyl acetone from the treated oil.

11. In the art of refining mineral lubricating oil containing parafilnic and naphthenic hydrocarbons, the step of fractionally extracting the oil with acetyl acetone, to eiiect a separation of fractions respectively richer in parafiinic and naphthenic compounds.

12. The process of treating a viscous fraction of a crude oil of one type containing paraflinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a great content of paraffinic hydrocarbons, which comprises extracting the viscous fraction with acetyl acetone and separating the oil so treated into portions respectively richer in paraflinic and naphthenic hydrocarbons.

13. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having the quality of a corresponding fraction of a parafiinic base crude, which comprises extracting the viscous fraction with acetyl acetone, and separating the oil so treated into portions respectively richer in paraffinic and naphthenic compounds.

14. In the art of refining mineral oils, the process which comprises adding acetyl acetone to a viscous oil liquid at ordinary temperatures containing paraffinic and naphthenic hydrocarbons, heating the mixture to a temperature sufficient to efiect solution, cooling the solution to a temperature sufficient to form two layers respectively richer in naphthenic hydrocarbons and paraffinic hydrocarbons other than wax, and separating the upper layer richer in paraffinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

15. In the art of refining mineral oils, the process which comprises bringing acetyl acetone into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing paraffinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation.

16. The process of decreasing the viscositygravity constant of a viscous mineral oil which comprises extracting the oil with a diketone.

17. The process of decreasing the viscositygravity constant of a viscous mineral oil at least 0015 which comprises extracting the oil with acetyl acetone.

18. The process of treating a viscous mineral oil of viscosity-gravity constant between substantially 0.850 and 0.875 to reduce the viscositygravity constant by a least 0.015, which comprises fractionally extracting said viscous oil with acetyl acetone.

'19. The processvofzireating 2. visous; minei a'k oil ioft' v'iscosityegravity constant: higher- .than 0:85i0nt'o produce an. oil having aiviscositygraw ityi -canstant lessz-than 0.830';{ which comprises" 5; fractionally extractinggsaid Viscous oil with acety l acetone. V

29. ThGV-DIOCBSSJOftreating a "viscous "mineral 011i; of tvisbosity-gliavitix"constafit 2 higher than? V V 0 ,835 to produce an: 011' having -a. viscosity: gravity constant of less than 0.828 which comprises?r fractionally extractingsa'id viscous: oilwith acetyl acetone. r V I v V SEYMOURW; FERRIS. 

